Convert::ToBase64CharArray Method (array<Byte>^, Int32, Int32, array<Char>^, Int32)

 

Converts a subset of an 8-bit unsigned integer array to an equivalent subset of a Unicode character array encoded with base-64 digits. Parameters specify the subsets as offsets in the input and output arrays, and the number of elements in the input array to convert.

Namespace:   System
Assembly:  mscorlib (in mscorlib.dll)

public:
static int ToBase64CharArray(
	array<unsigned char>^ inArray,
	int offsetIn,
	int length,
	array<wchar_t>^ outArray,
	int offsetOut
)

Parameters

inArray
Type: array<System::Byte>^

An input array of 8-bit unsigned integers.

offsetIn
Type: System::Int32

A position within inArray.

length
Type: System::Int32

The number of elements of inArray to convert.

outArray
Type: array<System::Char>^

An output array of Unicode characters.

offsetOut
Type: System::Int32

A position within outArray.

Return Value

Type: System::Int32

A 32-bit signed integer containing the number of bytes in outArray.

Exception Condition
ArgumentNullException

inArray or outArray is null.

ArgumentOutOfRangeException

offsetIn, offsetOut, or length is negative.

-or-

offsetIn plus length is greater than the length of inArray.

-or-

offsetOut plus the number of elements to return is greater than the length of outArray.

The subset of length elements of inArray starting at position offsetIn, are taken as a numeric value and converted to a subset of elements in outArray starting at position offsetOut. The return value indicates the number of converted elements in outArray. The subset of outArray consists of base-64 digits.

The base-64 digits in ascending order from zero are the uppercase characters "A" to "Z", the lowercase characters "a" to "z", the numerals "0" to "9", and the symbols "+" and "/". The valueless character, "=", is used for trailing padding.

The offset and length parameters are 32-bit signed numbers. The offsetIn and offsetOut parameters are zero-based array positions.

System_CAPS_importantImportant

The ToBase64CharArraymethod is designed to process a single byte array that contains all the data to be encoded. To create a base-64 character array from a byte stream, use the System.Security.Cryptography::ToBase64Transform class.

The following example demonstrates using the ToBase64CharArray method to UUencode (encode in base 64) a binary stream, then save the encoding to a file.

public:
   void EncodeWithCharArray()
   {
      FileStream^ inFile;
      array<Byte>^binaryData;

      try
      {
         inFile = gcnew FileStream( inputFileName,
                                    FileMode::Open,
                                    FileAccess::Read );
         binaryData = gcnew array<Byte>((int)(inFile->Length));
         long bytesRead = inFile->Read( binaryData, 0,
                                        (int)inFile->Length );
         inFile->Close();
      }
      catch ( Exception^ exp ) 
      {
         // Error creating stream or reading from it.
         Console::WriteLine( "{0}", exp->Message );
         return;
      }

      // Convert the binary input into Base64 UUEncoded output.
      // Each 3 Byte sequence in the source data becomes a 4 Byte
      // sequence in the character array. 
      long arrayLength = (long)((4.0 / 3.0) * binaryData->Length);

      // If array length is not divisible by 4, go up to the next
      // multiple of 4.
      if ( arrayLength % 4 != 0 )
      {
         arrayLength += 4 - arrayLength % 4;
      }

      array<Char>^ base64CharArray = gcnew array<Char>(arrayLength);
      try
      {
         Convert::ToBase64CharArray( binaryData,
                                     0,
                                     binaryData->Length,
                                     base64CharArray, 0 );
      }
      catch ( ArgumentNullException^ ) 
      {
         Console::WriteLine( "Binary data array is null." );
         return;
      }
      catch ( ArgumentOutOfRangeException^ ) 
      {
         Console::WriteLine( "Char Array is not large enough." );
         return;
      }

      // Write the UUEncoded version to the output file.
      StreamWriter^ outFile;
      try
      {
         outFile = gcnew StreamWriter( outputFileName,
                                       false,
                                       Text::Encoding::ASCII );
         outFile->Write( base64CharArray );
         outFile->Close();
      }
      catch ( Exception^ exp ) 
      {
         // Error creating stream or writing to it.
         Console::WriteLine( " {0}", exp->Message );
      }
   }

Universal Windows Platform
Available since 8
.NET Framework
Available since 1.1
Portable Class Library
Supported in: portable .NET platforms
Silverlight
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1
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